Patent GB-759870-A (GB)
Title: Method of making photographic emulsions for colour photography
IPC: G03C7/32
Filed: 1954-03-24
Abstract: 759,870. Photographic emulsions containing colour couplers. KODAK, Ltd. March 24, 1954 [March 26, 1953], No. 8537/54. Class 98 (2). A non-diffusing sulphamylbenzamido colour coupler is added either to a gelatino silver halide emulsion or to a water-soluble salt of a polymer containing salt-forming acid groups and the emulsion and polymer salt are mixed, the pH of the mixture is almost immediately brought below 7, and a styrene interpolymer (i.e. an interpolymer of styrene and an α: #-unsaturated dicarboxylic acid, e.g. maleic, acrylic, methacrylic or itaconic acid, including an acid in which part of the carboxyl groups have been converted to amide or imide derivatives or both) which is used as a water-soluble salt (e.g. the ammonium, sodium, potassium or lithium salt) and which complies with a specified test is added to the mixture with stirring to form a dispersion of particles of gelatin, styrene interpolymer and silver halide containing the colour coupler. The gelatin may contain an appreciable amount of a gelatin derivative, e.g. as described in Specification 649,545. The water-soluble polymer salt may be derived from methacrylic acidmethyl methacrylate copolymer, algin, carboxymethyl cellulose, or cellulose sulphate. The sulphamylbenzamido coupler has the formula wherein X is H or SO 2 NR 1 R 2 , R 1  and R 2  are H or alkyl, aminoalkyl or hydroxyalkyl groups, and Z is an organic radical containing a phenolic coupling function or an open-chain or closedring reactive methylene coupling function. Two such emulsions, each containing a different colour coupler and each sensitized to a different region of the spectrum may be mixed together and the third coupler incorporated in another layer by the method of Specification 541,589 or by simple dispersion. Alternatively, one coupler may be incorporated by the method of the invention and the remaining coupler or couplers incorporated in separate layers by the method of Specification 541,589 or by simple dispersion, or all three couplers may be incorporated in a single layer by the method of the invention or two by this method and the third in a surrounding silver halide emulsion in the same layer. The gelatin may be used in about 0.7 per cent aqueous solution and the water-soluble polymer and the styrene interpolymer may be present in amounts 1 to 2 times and 0.01 to 0.5 times that of the gelatin respectively. In one preparation, a mixture of 1-hydroxy-4-chloro-N-{ #-4-[2-(2: 4- di - tert. - amyl) - phenoxy - 5 - (3: 5 - dichlorosulphonyl) - benzamido - benzamido - phenyl - ethyl }-2-naphthamide, methanol, and monoethanolamine is heated to 55‹ C., and poured slowly into an agitated aqueous solution of gelatin and sodium alkylnaphthalene sulphonate. The mixture is milled, shredded and washed, dilute acetic acetic being used in the first washings. Another preparation is similar using 1 - phenyl - 3 -{ 3 - [2 - (2: 4 - di - tert. - amylphenoxy)-5-(3: 5-dichlorosulphonylbenzamido)- benzamido]-benzamido}-5. pyrazolone. In Example 1, the coupler dispersion of the first preparation, a red-sensitive gelatino silver halide emulsion, and distilled water, all preheated to 40‹ C., are stirred together. An aqueous solution of methyl methacrylate-methacrylic acid copolymer is added, and, after stirring, the pH is adjusted to 6.6 by the addition of aqueous citric acid. An aqueous solution of sodium alkylnaphthalene sulphonate is added, and after stirring an aqueous solution of styrene-maleamic acid copolymer, followed by further stirring. Finally, an aqueous solution of gelatin and saponin is added. In Example 2, the procedure is similar using the coupler dispersion of the second preparation and a green-sensitive emulsion. In Example 3, the coupler of the first preparation is dissolved in aqueous-methanolic sodium hydroxide and the filtered solution is added to an aqueous solution of methyl methacrylate-methacrylic acid copolymer. The remaining procedure is similar to that of Example 1. In Example 4, the procedure is similar to that of Example 3 using the coupler of the second preparation. In Example 5, the emulsion of Example 1, the emulsion of Example 2, a a gelatin dispersion of dioctylhydroquinone dissolved in dibutylphthalate, a methanol solution of benzthiazole methiodide, an aqueous solution of potassium bromide and iodide, an aqueous solution of saponin, and an aqueous solution of mucochloric acid are mixed and coated on a support. Diamylhydroquinone and didodecylhydroquinone may also be used as antistain agents. Specifications 711,488 and 757,368 also are referred to.